Planner (programming language)

Planner is a programming language designed by Carl Hewitt at MIT and first published in 1969. The name is often written in capitals in older publications, though it is not an acronym. It was created for the procedural embedding of knowledge, as a rejection of the resolution theorem proving paradigm, and it combined programmability with logical reasoning through pattern directed invocation, so that an implication could be run as forward or backward chaining. To save time and memory on the small computers of the day it relied on backtracking, a unique name assumption and a closed world assumption. A subset, Micro-Planner, powered Terry Winograd's SHRDLU program, and the full language was implemented as Popler at the University of Edinburgh. Derivations such as QA4, Conniver and QLISP were important tools in 1970s artificial intelligence research.